Ecology Letters (2010) 13: 597–605 Intensification or abandonment of agricultural land use has led to a severe decline of semi‐natural habitats across Europe. This can cause immediate loss of species but also time‐delayed extinctions, known as the extinction debt. In a pan‐European study of 147 fragmented grassland remnants, we found differences in the extinction debt of species from different trophic levels. Present‐day species richness of long‐lived vascular plant specialists was better explained by past than current landscape patterns, indicating an extinction debt. In contrast, short‐lived butterfly specialists showed no evidence for an extinction debt at a time scale of c. 40 years. Our results indicate that management strategies maintaining the status quo of fragmented habitats are insufficient, as time‐delayed extinctions and associated co‐extinctions will lead to further biodiversity loss in the future.

Biodiversity loss can affect the viability of ecosystems by decreasing the ability of communities to respond to environmental change and disturbances. Agricultural intensification is a major driver of biodiversity loss and has multiple components operating at different spatial scales: from in-field management intensity to landscape-scale simplification. Here we show that landscape-level effects dominate functional community composition and can even buffer the effects of in-field management intensification on functional homogenization, and that animal communities in real-world managed landscapes show a unified response (across orders and guilds) to both landscape-scale simplification and in-field intensification. Adults and larvae with specialized feeding habits, species with shorter activity periods and relatively small body sizes are selected against in simplified landscapes with intense in-field management. Our results demonstrate that the diversity of land cover types at the landscape scale is critical for maintaining communities, which are functionally diverse, even in landscapes where in-field management intensity is high.